The use of centerfolded film in conjunction with L-shaped sealing machines in either a horizontal or vertical configuration is a very common packaging technique today. Furthermore, the bulk of the film used in this method is shrink film, which shrinks to conform closely to the product when exposed to a proper source of heat (generally hot air jets). It is a characteristic of this packaging method that the air entrapped as the film shrinks will cause a "ballooning" effect and prevent the film from conforming to the product unless a bleeder hole is punched in the film to permit the entrapped air to escape. While this technique is acceptable for many products, there are many categories of products, such as perishable food items, where the use of a bleeder hole is not acceptable because it can permit dust contamination, or, in the case of certain meat products intended to be freezer-stored, it increases the likelihood of "freezer-burn."
There are other categories of perishable food products which are currently packaged in evacuated bags wherein considerable economies could be realized if it were possible to package these products directly on L-sealer equipment utilizing different types of new structured, co-extruded films in centerfolded configurations. The new air-evacuated system described below satisfies this requirement.